Philosophy of Mind is a potential influence on philosophical questions such as the nature of death, the nature of free will, the nature of what a person is, and the nature of emotion, perception and memory. The central issue in Philosophy of Mind is the mind-body problem, and the challenge is to explain how a supposedly non-material mind can influence a material body and vice-versa. The mind–body problem concerns the explanation of the relationship that exists between minds, or mental processes, and bodily states or processes.